The flow-ecology relationships that underpin environmental flows are not well understood, particularly at lower trophic levels. As a result, the ecological benefits of environmental flow actions are often assessed only for target species or are inferred. A broader understanding of environmental flow effectiveness requires investigation of specific interactions between the flow regime and stream biota.
Stream biofilms have been suggested as ideal bioindicators that are responsive to environmental conditions, ubiquitous, and ecologically significant but accurate identification of the diverse constituents of the stream periphyton can be challenging. Advances in molecular biology offer new opportunities to measure microbial community dynamics and evaluate stream health at the base of the food web.
We conducted an experiment in two coastal streams in Victoria to measure the response of stream biofilm to changes in flow. We provided artificial substrate for biofilm colonization over a series of three-week periods using wood blocks on floating frames and compared biofilms from a regulated stream reach to two unregulated reaches. We evaluated microbial community dynamics for 72 stream biofilm samples using multiple DNA barcodes (16S, 23S, ITS). We will describe observed patterns in community structure associated with physicochemical properties and changes in flow.